It is often necessary to provide an implanted medical device to assist an organ of a human or a non-human animal or as a substitute for the organ. Examples of such implanted device include a ventricular assist device (VAD) implanted in a patient's body to take over some or all of the pumping function of the heart as well as other cardiac assist devices and artificial heart pumps. While the devices are implanted within a patient's body, such devices may be supplied energy from an implanted or an external power source. Implanted power sources generally have limited power capacity due to constraints, such as size and weight. Thus, the internal power sources may need to be augmented or recharged continuously or at frequent intervals. A conventional manner for supplying intermittent or continuous power to the implanted device is to use a pair of induction coils. A secondary or receiving coil is implanted within the body. A primary or charging coil may be aligned externally with the receiving coil for transcutaneous energy transfer (TET).
TET involves power transfer across the skin without direct electrical connectivity. Because the electrical power is transmitted through the skin, the amount of power transmitted may be limited to avoid damaging the skin. Efficient transfer of power between the primary coil and the secondary coil requires proper orientation and alignment therebetween, which may be difficult to obtain because the secondary coil is implanted under the skin. The embodiments described below may alleviate one or more of these drawbacks.